Some new designs of mobile communication devices—such as smart phones, tablet computers, and laptop computers—contain two Subscriber Identity Module (SIM) cards that provide users with access to two separate mobile telephony networks while using only one radio frequency (RF) transceiver. Examples of mobile telephony networks include GSM, TDSCDMA, CMA2000, and WCDMA. Example multi-SIM mobile communication devices include mobile phones, laptop computers, smart phones, and other mobile communication devices that are enable to connect to multiple mobile telephony networks. A mobile communication device that includes two SIM cards and connects to two separate mobile telephony networks using only one RF transceiver is termed a “dual-SIM-dual-standby” (DSDS) device.
In a dual-SIM-dual-standby communication device (i.e., a DSDS communication device), the RF frontend is time shared between two subscriptions, each associated with a different mobile telephony network. Only one subscription may use the RF front end to communicate with its mobile network at a time. However, even when the subscriptions are in “standby” mode, meaning they are not currently receiving a network paging message, they still need to perform discontinuous reception (DRX) of network paging messages at regular intervals (i.e., a discontinuous reception period) in order to remain connected to the network. Therefore, it is possible that at a certain times, the two subscriptions may need to use the RF transceiver to communicate with their respective mobile network at the same time. For example, two subscriptions may try to access the RF frontend to receive their paging messages simultaneously, or one subscription may be using the RF frontend when the other subscription receives a network paging message.
The overlapping page reception that occurs when the DSDS mobile communication device receives network paging messages for both subscriptions at the same time is referred to herein as a “paging collision.” When a paging collision occurs, one subscription must be assigned the RF transceiver to the exclusion of the other subscription. In other words, one subscription may be blocked from communicating with its respective network in favor of the other subscription. Currently, the paging DRX cycle length (i.e., the length of time from the beginning of one network paging session to the next) for each subscription is determined entirely by the network and occurs in regular, predictable intervals. A DSDS communication device cannot manipulate or reschedule the paging DRX cycle for either subscription and, therefore, cannot avoid paging collisions that occur between two subscriptions.